Carrier resin for pigment pastes, preparation and use thereof

ABSTRACT

Carrier resin for pigment pastes, preparation and use thereof The invention relates to paste resins comprising (a) quaternary ammonium groups, (b) hydroxyl groups, (c) urethane radicals and (d) groups of the formula (I) ##STR1## in which R 1  to R 4  independently of one another represent hydrogen or a hydrocarbon radical of 1 to 10 carbon atoms and X denotes hydroxyl or a urethane radical, the average molecular weight (Mn) of these paste resins being 500 to 10,000. 
     The invention further relates to the preparation of these paste resins, their use for pigment pastes as well as these pigment pastes. Water-thinnable paints, especially electrocoating paints which comprise the pigment pastes according to the invention, furnish, from a variety of substrates, surfaces free from defects and comparable film thicknesses.

In the paint industry it is generally customary in the manufacture ofpigmented paints to grind the pigments in some of the binder intendedfor use as paint binder or in special binders (paste resins or pigmentcarrier resins) These so-called grinding pastes (or pigment pastes) arethen applied as paint together with the remaining binder. Such grindingpastes are particularly necessary for use with low-solventelectrocoating (EC) paints, since

1. high-pigmented grinding pastes with a low solvent content do notlastingly affect the solvent balance;

2. in the operation of the EC bath it has been found advantageous tocarry out the addition of the subsequent materials in two separatecomponents, viz. a high-pigmented colored component and a clearcoatcomponent. Any desired automatic control of the bath operation isthereby considerably facilitated;

3. pigments cannot usually be incorporated directly in an aqueousdispersion or in an EC bath. The reasons for this are many. On the onehand, (inadequately watted) pigments tend to agglomerate in aqueoussystems and to form correspondingly inadequate precipitates on thedeposited films (in particular on horizontal areas of the workpiece). Onthe other hand, pigments must be very finely ground (<10 μm, preferably<3 μm) to be able to form stable pigment dispersions at a correspondingwetting.

The paste resins used for grinding pastes of this type must possess anumber of characteristics. An important such characteristic is goodwetting power toward the particular pigments. They must furthermore befully compatible with the principal binder and they must notsignificantly alter the characteristics of the principal binder whenused in the required amounts. In addition, these paste resins shouldhave a relatively low viscosity. Furthermore, even high-pigmentedgrinding pastes with a pigment/binder ratio (PBR) of >2:1 preferably 6:1and particularly >12:1 should have a long shelf life, i.e. the pigmentsshould not sediment or form agglomerates. Nor should the pastes thicken(for example owing to developments of structural viscosity orthixotropy), since in practice they must remain pumpable over anextended period of time. It is furthermore advantageous to employ asspecial paste resins binders which are depositable under the conditionsprevailing in EC. This avoids enrichment of the bath and thus effluentcontamination. Also the paste resins deposited in this manner must notbe detrimental to film flow-out (for example by cratering) and curing.

AT patent 380,264 describes paste resins which are obtained by targetedmodification of low-molecular diepoxide or polyepoxide compoundscomprising oxazolidine groups. These systems are distinguished by highpigmentation, but they tend to develop thixotropy and structuralviscosity on aging.

EP Offenlegungsschriften 028,402 and 0,076,955 likewise disclose bindersbearing oxazolidine groups; however, a PBR of 3:1 cannot be exceededwithout agglomeration. US Patent 3,936,405 describes modified epoxyresins bearing onium groups, particularly quaternary ammonium groups asadvantageous paste resins. The grinding pastes obtainable therefromallow PBR of about 4:1 to be reached (Example XI).

EP Offenlegungsschriften 107,088, 107,089 and 107,098 likewise disclosesynthetic resins which bear quarternary ammonium groups and can be usedas higher pigmentable paste resins (PBR a 20:1). These paste resins havethe drawback, inter alia, that different film thicknesses and surfacequalities occur on different substrates despite identical depositionconditions.

The substrates particularly used in the automotive industry are blanksteel, zinc phosphated steel, hot-galvanized or electro-galvanized steelpanels and aluminium. The important criterion being that, apart fromdefect-free surfaces (for example the L-shaped panel test; no graining;no peaks or spots inter alia), comparable film thicknesses are alsoachieved. On aluminium in particular, known paste resins tend to formfilms which are thick and hence often porous.

EP Offenlegungsschrift 203,204 finally describes paste resins which areproducts of a reaction of aliphatic polyepoxides with polyether amines.Paste resins of this composition have a particularly good antifoameffect. 0n the other hand, they cannot reach very high and stabledegrees of pigmentation (PBR) In addition, the EC dispersions requirespecial anticratering agents where the above binder combinations areused.

It has now been found, surprisingly, that the foregoing drawbacks may besubstantially avoided by using paste resins based on modifiedcyclocarbonate compounds with quaternary ammonium groups.

Accordingly, the invention relates to paste resins comprising (a)quaternary ammonium groups, (b) optionally hydroxyl groups, (c)urethanes of the formula ##STR2## wherein R₅ is a hydrocarbon optionallyinterrupted with --O-- and (d) groups of the formula (I) ##STR3## inwhich R¹ to R⁴ independently of one another represent hydrogen or ahydrocarbon radical, preferably a (cyclo)-alkyl radical, of 1 to 10carbon atoms, preferably 1 to 6 carbon atoms, and X denotes hydroxyl ora urethane radical,

the average molecular weight (Mn; determined by gel chromatography; PSstandard) of these paste resins being 500 to 10,000.

The subject matter of the invention is furthermore a process for thepreparation of these paste resins, their use in pigment pastes as wellas these pigment pastes.

The paste resins according to the invention preferably have an averagemolecular weight (M_(n)) of 1,000 to 5,000. The hydroxyl values are notmore than 10 to 200, preferably 20 to 90 mg of KOH/g and the amount ofquaternary nitrogen per gram generally is 0.2 to 20, preferably 0.8 to 5milliequivalents.

The number of the groups (a) per molecule (statistical average) isgenerally between 1 to 4, preferably 2 or 3, the number of the groups(b) between 1 and 20, preferably 2 to 8, the number of the groups (c)between 1 to 6, preferably 2 to 4 and the number of the groups (d)between 1 to 6, preferably 2 to 4.

The urethane radicals (c) and X in the formula (I) are derived primarilyfrom the long-chain monoisocyanates (D₁) described in greater detailbelow, i.e. from monoisocyanates usually of 6 to 22 carbon atoms,preferably 10 to 18 carbon atoms, which from the very beginning containonly one isocyanate group, and/or from diisocyanates or polyisocyanateshaving one free isocyanate group whose remaining isocyanate group(s) isor are stably masked (i.e. it does not or they do not become demasked oncuring) and whose total number of carbon atoms is generally about 10 to50, preferably 20 to 40. In contrast, the paste resins, especially ifthey are self-curing, can also contain other isocyanate radicals whichare derived from optionally short-chain, partly masked diisocyanates orpolyisocyanates (D_(z)), which under the curing conditions lose theirmasking groups. The term urethane radical is understood to be the group##STR4## in which R⁵ denotes a hydrocarbon radical particularly of analiphatic or araliphatic character of 6 to 50, preferably 10 to 40 andparticularly 10 to 30 carbon atoms, which radical can be optionallyinterrupted by heteroatoms (O, NH, NR) or groups such as ##STR5##

In the case of the (partly) masked polyisocyanates, R⁵ also carries oneto five, preferably one to three, masked isocyanate groups. In thisvariant this radical R⁵ can also be aromatic and then has not more than6 to 25, preferably 6 to 15, carbon atoms.

The preparation of the paste resins according to the invention can becarried out in that polyamines (A) are first reacted with compounds (B)which contain at least one cyclic carbonate group (2-oxo-1,3-dioxolanegroup) and optionally hydroxyl groups, 1,2-epoxide groups and isocyanategroups, in such a manner that this reaction product (C) still containsquaternizable amino groups, and this reaction product (C) is thenquaternized, optionally after a prior reaction with monofunctionalisocyanates (D1)/(D2).

The number of carbon atoms in the polyamines (A) is generally 2 to 40,preferably 2 to 20.

In case these polyamines are more than difunctional toward the compounds(B) and the latter contain two cyclic carbonate groups, the reactionconditions should be chosen such that no gelling occurs. Suitablepolyamines (A) are preferably those which contain at least one freeprimary amino group (A1) and also additionally contain secondary and/ortertiary amino groups (A1).

Polyamines (A1) which contain secondary amino functions in addition tothe primary amino functions, may be converted to tertiary groups afterthe reaction with the component (B) and prior to the reaction with theisocyanates, for example with the monoepoxide compounds described ingreater detail below (preferably ethylene oxide, propylene oxide,2-ethylhexyl glycidyl ether, glycidyl versatate); alternatively they mayalso be reacted with the isocyanates to form urea structures.

Those polyamines are also suitable as polyamines (A), for example, whichcontain only primary amino groups and preferably are diprimary (A2).These polyamines (A2) are preferably used in admixture with thepolyamines (A1), particularly primary/tertiary diamines. In theirreaction with an at least difunctional compound (B), the latter act aschain stoppers.

The polyamines (A1)/(A2) may be also represented by the followingformula (II) ##STR6## wherein

p is zero or an integer of 1 to 6, preferably 1 to 4,

R₅ represents a divalent, preferably non-aromatic hydrocarbon radical of2 to 18 carbon atoms, preferably a branched or straight-chain alkyleneradical of 2 to 10 carbon atoms, particularly of 2 to 6 carbon atoms, ora cycloalkylene radical of 5 to 12 carbon atoms, preferably 6 to 10carbon atoms, or an aralkylene radical of 7 to 12 carbon atoms,preferably 8 to 10 carbon atoms, or a polyoxyalkylene radical of 2 to 18carbon atoms, and

R₇, R_(7') independently of one another represent H or ##STR7## in whichR₆ has the same meaning as before, and R₈, R₉ either independently ofone another represent H, (C₁ -C₂₀)alkyl, preferably (C₁ -C₆)alkyl,hydroxy(C₁ -C₁₆ )alkyl, preferably ##STR8## (C₁ -C₁₂)alkyl, --CH₂--O--(C₁ -C₁₂)alkyl, --CH₂ --O--aryl, ##STR9## or R₈ and R₉ are part ofa 5-, 6- or 7-membered aliphatic ring, with the proviso that when p iszero, R₇ ' is not H.

In addition, polyamines of the formula (III)

    A--(R.sub.6 NH).sub.p --R.sub.6 B                          (III)

in which A, B=NH₂ or OH, at least one of these two radicals representingNH2 however, and R₆ and p having the same meaning as in the formula(II), are also suitable polyamines.

Furthermore, the polyamines and polyaminopolyols, for example thosedescribed in DE patent applications P 36 44 371.9 (HOE 86/F 319), P 3726 497.4 (HOE 87/F 233) and P 38 09 695.1, are also suitable. Theseliterature sources, including the preferred embodiments describedtherein, are referred to herewith. In addition, polyaminoamides orcondensation products of diprimary amines with dicarboxylic acids (suchas adipic acid or dimeric fatty acid) and polyglycol polyamines or amineadducts, such as amine-epoxy resin adducts, are also suitable.

Examples of suitable polyamines (A) are: ethylenediamine,propylenediamine, 2-methylpentamethylenediamine, pentamethylenediamine,hexamethylenediamine, trimethylhexamethylenediamine, neopentyldiamine,octamethylenediamine, triacetonediamine, dioxadecanediamine,dioxadodecanediamine and higher homologs, cycloaliphaticdiamines such as1,2-, 1,3- or 1,4-cyclohexanediamine;4,4'-methylene-bis-cyclohexylamine,4,4-isopro-pylene-biscyclohexylamine, isophoronediamine,tricyclododecenyldiamine, menthanediamine,4,4,-diamino-3,3,-dimethyldicyclohexylmethane,3-aminomethyl-1-(3-aminopropyl-1-methyl)-4-methylcyclohexane,N-methylethylenediamine, N-aminoethylpiperazine, 2-aminoethylpiperazine,N,N-dimethylethylenediamine, N,N-dimethylpropylenediamine,N,N-dimethylaminopropylamine,N,N-bisaminopropyl-N',N'-dimethylaminopropylamine,N,N-dihydroxyethylethylenediamine, aromatic amines such asm-xylylenediamine, aliphatic poly(tri-, tetra-)amines such asdiethylenetriamine, dipropylenetriamine, bishexamethylenetriamine,triethylenetetramine,tetraethylenepentamine,pentaethylenehexamine,methyliminobispropylamine, N-alkylaminodipropylenetriamine (alkyl=CH₃ -,CH₃ -, C₄ H₅ -, (CH₃)₂ N-(CH₂)₃), tetrapropylenepentamine; furthermorealkanolamines such as monoethanolamine, dietnanolamine,aminoethylethanolamine, N-(2-hydroxypropyl)ethylenediamine, mono-, di-(nor iso)propanolamine, ethyleneglycol bis-propylamine, neopentanolamine,methylethanolamine, 2-(2-aminoethoxy)ethanol,hydroxyethylaminoethylamine, hydroxyethyldiethylenetriamine,3-aminopropyltrialkoxysilane (alkoxy=methoxy, ethoxy, tridecyloxy),2-amino-2-hydroxymethyl-1,3-propanediol, polyoxypropylenediamine(preferably with an average molecular weight of about 200 to 400),aromatic amines such as (m)-xylylenediamine and the like. Examples ofpreferred polyamines (A1) which can be used, as can the polyamines (A2),in admixture with one another, are: N,N-bisaminopropyl-N-methylamine,N-aminopropylmethylamine, N-aminopropylpropylamine, tallow fatpropylenediamine and especially dimethylaminopropylamine anddiethylaminopropylamine. Any materials can be used as the compounds (B),provided they contain on average at least one, preferably two or threecyclic carbonate (2-oxo-1,3-dioxolane) groups per molecule and have noother functional groups which could interfere with the reaction with thecomponent (A). The molecular weight M_(n) (average number, determined bygel chromatography, PS standard) should generally be between 100 and10,000, preferably between 150 and 3,500 and the 2-oxo-1,3-dioxolaneequivalent weight between 100 and 1250. The cyclic carbonate groups arepreferably terminal, but in some cases it is also possible to usecompounds as components (B) which contain these groups statisticallydistributed over the molecular chain and which can be prepared bycopolymerization using olefinically unsaturated compounds containingthese cyclic carbonate groups. DE Offenlegungsschrift 3,644,373, forexample, describes such a method of preparation.

The component (B) preferably has the general formula (IV) ##STR10##wherein R¹² denotes a z-valent radical of a polyether, polyether polyol,polyester, polyester polyol which can also optionally contain (NR¹³)groups, R¹³ representing hydrogen, alkyl of 1 to 14, preferably 1 to 8carbon atoms or hydroxyalkyl of 1 to 14, preferably 1 to 8 carbon atoms,and these radicals generally having average molecular weights M_(n) of200 to 5000, preferably 200 to 2000, or a z-valent hydrocarbon radical,preferably an alkylene radical of 2 to 18 carbon atoms which canoptionally carry inert or noninterfering groups, or

a z-valent poly(sec.)amine radical or

the z-valent radical of a reaction product of an epoxide-carbonatecompound with polyamines, polyols, polycaprolactone polyols, hydroxylgroup-containing polyesters, polyethers, polyglycols,hydroxyl-function-, carboxyl function- and amino function-containingpolymeric oils having average molecular weights M_(n) of 800 to 10,000,polycarboxylic acids, hydroxyl function- or amino function-containingpolytetrahydrofurans, or of reaction products of polyamines withglycidyl esters of α,α-dialkylalkanemonocarboxylic acids having theempirical formula C₁₂₋₁₄ H₂₂₋₂₈ O₃ or with glycidyl versatate, thesereaction products generally having average molecular weights M_(n) of300 to 12,000, preferably 400 to 5000,

z denotes 1 to 5.

In this formula (IV) the index z preferably represents 2 or 3,preferably 2.

The term "radical" in the forgoing sense is understood to mean theparticular compound (for example polyether) less the active hydrogenatoms of those groups which are adjacent to the CH₂ group in the formula(IV).

Compounds of that type and their preparation are described, for example,in DE patent application P 37 26 497.4 (HOE 87/F 233) to which referenceis made here.

Preferred starting materials for the preparation of the cycliccarbonates (IV) and the optionally used mixed epoxide-carbonatecompounds (V) are the polyglycidyl ethers of polyphenols, for examplebisphenol A or bisphenol F. The glycidyl ethers are obtained, forexample, by reacting a polyphenol with epichlorohydrin.

Examples of polyphenols are bis(4-hydroxyphenyl)-2,2-propane,bis(4-hydroxyphenyl)methane, 4,4,-dihydroxybenzophenone,bis(4-hydroxyphenyl)-1,1,-ether, bis(4-hydroxyphenyl)-1,1'-isobutane,bis(2-hydroxynaphthyl)methane and 1,5-dihydroxynaphthalene. Thepolyglycidyl ether of the polyphenol preferably contains free hydroxylgroups additional to the epoxide groups. Diglycidyl adducts of (cyclic)ureas may also be used for this purpose.

In some cases it may be expedient to use as the component (B)additionally or, optionally, on their own mixed epoxide-carbonates, suchas those of the general formula (V) ##STR11## in which R¹² has themeaning of CH₂ --R¹² --CH₂.

Provided that the compounds (B) contain hydroxyl groups, they mayalready be reacted in this stage partially or completely with theisocyanates (D1)/(D2). This is, however, only then necessary, if theadduct (C), described in greater detail below still contains freeprimary and/or secondary amino groups suitable for quaternization whichotherwise would preferably react with the isocyanate. On the other hand,if the adduct (C) contains only tertiary or masked primary/secondaryamino groups, or a sufficient number of tertiary amino groups areavailable for the quaternization so that the primary/secondary aminogroups can react first, the reaction with the isocyanates (D1)/(D2)preferably takes place first in the case of this adduct (C).

To prepare this adduct (C), the components (A) and (B) are reacted inthe required stoichiometric ratios or amounts at elevated temperatures,for example at 50° to 140° C., preferably at 50 to 100° C., and in thepresence or absence of catalysts and preferably in inert solvents. Thereaction is generally allowed to proceed until, for example, a constantor the theoretical amine value is attained. Care must be taken that nogelling occurs. The components (A) and (B) are preferably used in suchamounts that 0.8 to 1.5 equivalents of primary amino groups are presentper 1 equivalent of cyclic carbonate groups. As an example, a preferredreaction system has the following composition:

(A1) : 28-80, preferably 40-70 mole %;

(A2) : 0-40, preferably 0-30 mole %;

(B) : 20-72, preferably 30-60 mole %.

(The data refer to the solid resins (C))

While in general no catalyst is necessary for the reaction of theprimary amino groups of the component (A) with the 2-oxo-1,3-dioxolanegroups of the component (B), it is expedient to use a catalyst for thereaction of the less reactive secondary amino groups, provided these arepresent in the component (A). Suitable catalysts for this purpose arestrongly basic compounds such as quaternary ammonium compounds, forexample alkyl-, aryl-, and/or benzylammonium hydroxides and alkyl-,aryl- and/or benzylammonium carbonates. Specific representatives ofquaternary ammonium compounds are in this connectionalkylbenzyldimethylammonium hydroxide (alkyl=C₁₆ -C₂₂),benzyltrimethylammonium hydroxide and tetrabutylammonium hydroxide.

Preferred catalysts are strongly basic amines, for examplediazabicyclooctane (DABCO), guanidine etc. In addition, the so-calledsupranucleophilic catalysts, for example 4-pyrrolidinepyridine andpoly(N,N-dialkylaminopyridine) are also suitable for this purpose; cf.the article by R. A. Vaidya et al. in Polymer Preprints, Vol 2 (1986),pp. 101-102.

Suitable solvents for the above reaction are preferably aprotic and,optionally, polar solvents. Examples of these are: halogenatedhydrocarbons (less suitable for use in dip paints), N-methylpyrrolidone,ethers such as diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran ordimethyl diglycol, dioxane; ketones, for example acetone, methyl ethylketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanoneand the like; esters (less suitable for use in dip paints), such asbutyl acetate, ethylglycol acetate and methoxypropyl acetate;(cyclo)aliphatic and/or aromatic hydrocarbons such as hexane, heptane,cyclohexane, benzene, toluene, the various xylenes as well as aromaticsolvents boiling in the range of about 150 to 180° C. (higher-boilingmineral oil fractions such as Solvesso®). The solvents may be usedsingly or mixed.

The stoichiometric evaluation of the starting products and theevaluation of the reaction products as to the progress of the reactionare based in the case of the component (A) on the amine value, usuallydetermined by perchloric acid titration, and in the case of thecomponent (B) on the cyclocarbonate equivalents value, usuallydetermined by titration with potassium hydroxide solution. Regardingfurther details of the preparation, reference should be made to the DEpatent application P 37 26 497.4 (HOE 87/F 233), already mentioned, andto EP Offenlegungsschrift 234,395 (HOE 87/F 159J).

Compounds based on reaction products of amines and cyclic carbonatesaccording to the patent applications mentioned above as well as DEOffenlegungsschrift 3,644,370 (HOE 86/F 318) are basically also suitableas the adducts (C) for the present invention, provided that they fallwithin the molecular weight range according to this invention andcontain a sufficient number of quaternizable amino groups.

The reaction of the adduct (C) with the isocyanates (D1)/(D2) takesplace under conditions which are customary for these types of reaction,expediently at 30 to 80° C. and in the presence of inert, preferablyaprotic solvents, for example those described above. The reaction isterminated when an NCO content of <0.2 % is reached.

The maximum number of the equivalents of isocyanate used is expedientlygoverned by the following criterion:

    ______________________________________                                        n(B)    =     hydroxyl functionality of the component (B) per                               mole;                                                           n(A + B)                                                                              =     hydroxyl functionality which is formed per mole                               of (C) according to the reaction (A) + (B);                     n(D)    =     equivalents of isocyanate (from D1 and D2) per                                mole of (C);                                                    n(D)    =     n(B) + n (A + B);                                               (D1):         0-4 equivalents per mole of compound (C),                                     preferably 1-2;                                                 (D2):         0-4 equivalents/mole of compound (C), prefer-                                 ably 0-2.                                                       ______________________________________                                    

The long-chain monoisocyanates (D1) which are intended to impart to thecompounds according to the invention, above all, an adequate measure ofa lyophilic character in addition to a degree of flexibility, usuallyhave 6 to 22 carbon atoms, preferably 10 to 18 carbon atoms; theirhydrocarbon radical preferably possesses an aliphatic or araliphaticcharacter. Appropriate examples are octadecyl isocyanate, dodecylisocyanate, nonylphenyl isocyanate etc.

Partly masked polyisocyanates still having one free NCO group and atotal number of carbon atoms of 10 to 50, preferably 20 to 40, are alsoa possible alternative. For example, the compounds listed below at (D2)may be used as polyisocyanates, preferably diisocyanates.Correspondingly, longer-chain compounds which are normally not split offduring the curing of the paint film, are suitable for masking. Examplesof these are fatty amines such as tallow fatty amine, octadecylamine ordodecylamine, nonylamine, isononyloxypropylamine or the correspondinglyderived alcohols, for example octadecyl alcohol, hexyl glycol and thelike. Special polyether alcohols, for example the ethoxylated octyl andnonyl phenols, known as wetting agents (for example Triton-X®orArkopal-N®), may be also used.

If the paste resins according to the invention are self-curing, then thereaction product (C) or even the component (B) may be also reacted withthe partly masked isocyanates (D2) which may also have a shorter chainand may become demasked under the curing conditions.

Any polyisocyanates known in the polyurethane or paint sector, forexample aliphatic, cycloaliphatic or aromatic polyisocyanates, aresuitable polyisocyanates for this purpose. Typical examples of suchpolyisocyanates are:

Xylylene diisocyanate, diphenylmethane-4,4-diisocyanate,triphenylmethyl-4,4'-triisocyanate, triphenylmethane triisocyanate,polyphenyl polymethylisocyanate, 2,2,4(2,4,4)-methylcyclohexyldiisocyanate, dicyclohexylmethyl diisocyanate, diethylfumarhexylisocyanate, bis(3-methyl-4-isocyanatocyclohexyl)methane,2,2-bis(4-isocyanatecyclohexyl)propane, the methyl ester of the lysinediisocyanate, the biuret of the hexamethylene diisocyanate,diisocyanates of dimeric acids, 1-methylbenzene-2,4,5-triisocyanate,biphenyl-2,4,4'-trisocyanate, the triisocyanate obtained from 3 mole ofhexamethylene diisocyanate and 1 mole of water having a 16% NCO content,and other compounds containing at least two NCO groups per molecule,preferably isophorone diisocyanate, hexamethylene diisocyanate,trimethylhexamethylene diisocyanate and tetramethylhexamethylenediisocyanate, but in particular 2,4-tolylene diisocyanate or2,6-toluylene diisocyanate or mixtures of these compounds.

In addition to these simple polyisocyanates, those isocyanates are alsosuitable which contain heteroatoms in the radical linking the isocyanategroups. Examples of these are polyisocyanates which comprisecarbodiimide groups, allophonate groups, isocyanurate groups, urethanegroups, acylated urea groups or biuret groups.

Finally, suitable polyisocyanates are also the known prepolymerscontaining terminal isocyanate groups, available in particular by thereaction of the simple polyisocyanates mentioned above, especiallydiisocyanates, with excesses of organic compounds having at least twogroups reactive toward isocyanate groups. These prepolymers, however,are preferably used as external curing components in non-self-curingsystems.

The masking agents should be such that at the customary curingtemperatures of 130° to 180° C., in the presence or absence of catalystsknown for this purpose, they again split off. Examples of such maskingagents are: aliphatic, cycloaliphatic or alkylaromatic (monohydric)alcohols, for example lower aliphatic alcohols such as methyl and ethylalcohol, the various propyl, butyl and hexyl alcohols, heptyl, octyl,nonyl and decyl alcohol and the like; methoxy-1-propanol andmethoxy-2-propanol; also unsaturated alcohols such as allyl alcohol,propargyl alcohol, cycloaliphatic alcohols such as cyclopentanol,cyclohexanol, alkylaromatic alcohols such as benzyl alcohol,methylbenzyl alcohol, p-methoxybenzyl alcohol and p-nitrobenzyl alcholand monoethers of glycols, such as ethylene glycol monoethyl ether,ethylene glycol monobutyl ether and the like. Further masking agents areketoximes, expediently those of 3 to 20 carbon atoms, preferably 3 to 10carbon atoms, such as acetoxime, methyl ethyl ketoxime (=butanoxime),hexanoxime (such as methyl butyl ketoxime), heptanoxime (such as methyln-amyl ketoxime), octanoxime and cyclohexanoxime, (CH-acid compoundssuch as alkyl malonates, acetoacetic esters such as cyanoacetic estershaving in each case 1 to 4 carbon atoms in the ester group, NH-acidcompounds such as caprolactam, amino alcohols such asdiethylethanolamine, and special amines such as dibutylamine.2-Ethylhexanol, butyl diglycol, butyl glycol and3-methyl-3-methoxybutanol are preferred.

Examples of suitable demasking catalysts are lead octoate, leadsilicate, lead naphthenate, zinc compounds according to the DEOffenlegungsschriften 2,807,698 and 3,306,064, zinc compounds andzinc-lead compounds of nitrophthalic acid, complex compounds obtainedfrom zinc oxide and 8-hydroxyquinoline (also usable in situ), antimonytrioxide, manganese (II) and manganese (III) acetlyacetonate, manganesephosphate, manganese-zinc phosphate, cobalt naphthenate, cadmiumacetylacetonate, thallium dicyclopentadiene, triethanolamine titanate ororganic compounds of tin, for example dibutyltin dilaurate andpreferably dibutyltin oxide.

The urethane group-containing products (C) obtained in this manner canbasically be quaternized by any methods known for this purpose, such asthose, for example, described in DE Offenlegungsschrift 2,641,286.However, the nature of the counterions introduced may lead tolimitations. Thus, quaternizing methods for paste resins according tothe invention to be used in electrocoating paints cannot be employed ifthey introduce halogen anions, since these lead to pronounced anodecorrosion. This is true, for example, in the case of quaternizationusing alkyl halides (iodides), but not, however, when using dialkylsulfates or trialkyl phosphates.

This quaternization is preferably carried out by reacting (C) withmonoepoxide compounds, for example ethylene oxide, propylene oxide,2-ethylhexyl glycidyl ether, glycidyl versatate, glycidyl phthalimide,phenyl glycidyl ether, methylglycidyl ether, phenol-(EQ)₅ glycidyl etherin the presence of preferably organic acids and preferably 0.5 to 20mole of H₂ O per mole of amino group (cf. in this connection alsoHouben-Weyl, vol. XI/2, p. 609 ff (1958)).

The acids used have a pK_(a) value of ≦6 and are expediently wellmiscible with water. Examples of these are inorganic acids such asphosphoric acid; however, organic acids, such as formic acid, aceticacid and in particular lactic acid, are preferred. It is also possible,for example, to carry out first the reaction of (C) with the monoepoxidecompound- under neutral conditions and only add the acid subsequently.

Quaternization is generally carried out at temperatures of 20° to 100°C., preferably 50° to 100° C., advantageously in the presence of anorganic solvent. In a preferred embodiment, for example, a mixture of 1mole of lactic acid/mole of the amino group to be quaternized and 0.5 to20, preferably 2 to 10 mole of demineralized water/mole of the aminogroup to be quaternized is slowly added to a mixture of the reactionproduct (C) and the monoepoxide compound (1 mole per mole of tertiaryamino groups or 2 mole per mole of secondary amino groups), in a proticsolvent, preferably butyl glycol, methoxypropanol and/or ethoxypropanol.The reaction is carried out until an acid value of <10 is reached.

In the case of readily volatile epoxide compounds, the mixture of lacticacid, water and solvent is first added and the epoxide compound(ethylene oxide, propylene oxide etc.) is introduced subsequently(pressureproof apparatus) with occasional cooling.

The compounds quaternized in this manner are highly suitable for use aspaste resins for pigment pastes and pigment dispersions, pigment:pasteresin ratios of 1:1 to 40:1, preferably 12:1 to 20:1 being possible,depending on the type of pigment, its primary particle size etc. Apartfrom the paste resin according to the invention and the pigment, thesepigment pastes may also contain the customary additives, such asfillers, other auxiliary substances commonly added to paints(dispersants, wetting agents, solvents, plasticizers, antifoams, etc.)as well as, optionally, a part or all of the known curing catalysts.

Suitable pigments are those commonly used for this purpose, for exampletitanium oxide (usually the main component), other white pigments andextenders, such as antimony oxide, zinc oxide, basic lead carbonate orlead silicate and/or lead sulfate, barium carbonate, clay, calciumcarbonate, aluminum silicate, silica, magnesium carbonate and/ormagnesium silicate; furthermore (addition) colored pigments such asphthalocyanin blue, hydrated iron oxides, chrome yellow, carbon black,toluidine red and manganese dioxide.

The water content of such pigment pastes depends on the viscositydesired for the processing and usually is between 10 and 50%.

If convenient, the pigment paste may also be further diluted prior touse.

The preparation of such pigment pastes is carried out in a known manner,such as that described in DE patent application P 37 26 497.4 (HOE 87/F233) or in the DE Offenlegungsschrift 2,634,229.

Comminution of the pigment is usually performed in ball mills, sandmills, Cowles dissolvers or continuous trituration equipment, until thepigment has been reduced to the desired particle size; it is then wettedby the carrier resin or dispersed in it. After the comminution theparticle size of the pigment should be in the region of 10 micrometersor less, preferably as small as possible. The pigment is generallyreduced to a fineness of less than 3 μm (measured by laser aerosolspectroscopy), preferably in the presence of glass beads, Al₂ O₃(corundum) beads, ceramic beads or ZrO₂ beads (diameter 0.5-3 mm).

The foregoing pigment dispersions (pigment pastes) are then added withmixing in the usual manner and in sufficient amounts to thewater-thinnable paint, in particular electrocoating paint. The finished,electrically depositable composition generally has a pigment to binder(=electrically depositable resin plus paste resin) ratio of 0.05:1 to0.8:1.

Suitable film-forming resins for these paints are the products known forthis purpose, such as those described, for example, in DE patentapplications P 36 44 371.9, P 37 26 497.4 and P 38 09 655.1 as well asin EP Offenlegungsschrift 234 395. Other resins suitable for thispurpose are disclosed in Journal of Coatings Technology, vol. 54, No.686, (1982), pp. 33 to 41 ("Polymer Compositions for CationicElectrodepositable Coatings"), to which reference is also made.

The electrical deposition of the paint particles from the electrocoatingpaints is carried out by known methods to which reference is made here.The deposition can take place on all electrically conducting substrates,for example metals such as steel, copper, aluminum and the like.

After deposition, the coating is cured by usual processes at elevatedtemperatures which generally depend on the nature of the curingcomponents, temperatures of 100 to 220° C., preferably 130 to 180° C.,being used.

The resulting coatings are distinguished particularly by an outstandingresistance to salt spray (ASTM-B-117-64; 960 hours on zinc phosphatedand blank steel panel).

Owing to the conversion of the quaternary ammonium structure into atertiary amine, on baking, the paste resins according to the inventionfurnish no cleavage products which lead to chain termination. Areduction of the polarity of the paint film with its consequent increasein water resistance is also linked to this conversion.

EXAMPLES

All indications of quantities are in parts by weight.

The sieve residue and the L-shaped panel coating are determined orperformed as follows:

Sieve residue

1 liter of the diluted paint solution is poured through a weighed perlonsieve (mesh size 30 μm). The sieve is rinsed with deionized water andweighed after drying (1 h/125° C.). The result is reported in mg ofresidue (based on 1000 ml of the bath).

L-shaped panel coating

A zinc phosphated steel panel (about 10 x 20 cm) is bent at a rightangle at its lower end (a 3 cm horizontal area). The panel is immersedin the coating bath in such a manner that the horizontal arm of the L isabout 15 cm below the surface of the paint bath. The coating is carriedout with the mixing action switched off and with a coating time of 4minutes. At the end of the coating period the panel remains in the bathfor a further 2 minutes. The panel is subsequently withdrawn from thebath, after a further 2 minutes rinsed with water and baked. The panelis visually assessed for flow-out, luster and sedimentation phenomena.

I. Preparation of the paste resin according to the invention

1.) Partly masked polyisocyanate (D2) 124 parts (1.05 equivalents of OH)of butyl glycol are slowly added to 174 parts of toluylene diisocyanate(2 equivalents of NCO, 80% of the 2,5-isomer, 20% of the 2,6-isomer) at25 to 40° C. in the presence of 0.01% of triethylamine as catalyst andthe reaction is allowed to proceed until an NCO value of about 13.5 to14.0% is reached.

2.) Synthesis of the compound (C)

2.1.) 204 parts of N,N-dimethylaminopropylamine (2 mole, 2 equivalentsof primary amine) were added at about 60° C. to 1048 parts of abiscarbonate based on Epicote® 1001 (1 mole, 2 equivalents of carbonate)in 537 parts of N-methylpyrrolidone in the course of one hour. Thereaction mixture was then kept at this temperature for about 3 to 5hours (amine value about 94/solid binder). The 70% resin mixture couldthen be further processed.

2.2.) A mixture consisting of 204 parts of N,N-dimethylaminopropylamine(2 mole, 2 equivalents of primary amine) and 176 parts of4,7-dioxadecane-1,10-diamine (1 mole, 2 equivalents of primary amine)was added at about 60° C. to 920 parts of a biscarbonate based onEpicote® 828 (2 mole, 4 equivalents of carbonate) in 557 parts ofN-methylpyrrolidone in the course of 1 hour. The reaction mixture wasthen kept at this temperature for about 3 to 5 hours (amine value about90/solid binder). The 70% resin mixture could then be further processed.

3.) Reaction of the compound (C) with isocyanate (D1)/(D2)

x parts of the octadecyl isocyanate (D1) and y parts of the partlymasked isocyanate (D2) in accordance with example 1) were added at 60 to70° C. to the reaction mixtures obtained above in 2.) in the course ofone hour in accordance with the Table 1 below. The reaction mixture wasthen kept at this temperature until an NCO value of virtually 0% wasreached.

                  TABLE 1                                                         ______________________________________                                        Example           3.1     3.2      3.3                                        ______________________________________                                        Initial compound  2.1.    2.1.     2.1.                                       according to example:                                                         x parts of octadecyl                                                                            590     590      590                                        isocyanate                                                                    (mole/equivalents of NCO)                                                                       (2/2)   (2/2)    (2/2)                                      y parts of isocyanate                                                                           --      596      596                                        according to example 1                                                        (mole/equivalents of NCO)                                                                       --      (2/1.9)  (2/1.9)                                    Amine value (solid binder)                                                                      62      47       45                                         Solids content (in %;                                                                           78      82       82                                         1 h, 125° C.)                                                          nA                2-2.5   2-2.5    --                                         n(A + B)          2       2        4                                          ______________________________________                                    

4.) Quaternization

The binder preliminary stages obtained in 3.) (for amounts see Table 2below) were introduced in a reaction vessel set to an overpressure of atleast 10 bar in an atmosphere of nitrogen. A mixture consisting of 102.2parts of 90% lactic acid (2 mole), 26 parts of demineralized water (atotal of 2 mole) and x parts of butyl glycol were then added in thecourse of 20 minutes at 50° C. with occasional cooling. 10 parts ofethylene oxide (0.228 mole) and nitrogen were passed into thisthoroughly homogenized mixture. This caused the temperature to rise; itwas kept at 100 to 120° C. with occasional cooling. The reaction mixturewas subsequently cooled to 70 to 80° C. and the remaining amount ofethylene oxide (about 166 parts; 3.772 mole) was passed in the course of2 hours.

The reaction was terminated when an acid value of about 10 to virtuallyzero was reached (some further 2 to 4 hours). The excess ethylene oxidewas then distilled off, the solids content was subsequently adjustedusing y parts of demineralized water and the mixture was cooled.

                  TABLE 2                                                         ______________________________________                                        Example            4.1     4.2       4.3                                      ______________________________________                                        Initial compound   3.1.    3.2.      3.3.                                     according to example:                                                         Parts by weight    2379    2975      2943                                     Parts of butyl glycol                                                                            107     306       268                                      Parts of demineralized water                                                                      56     112       208                                      Solids content      70      70        70                                      (in %; 1 h, 125° C.)                                                   Viscosity (DIN 53 019)                                                                           310     280       320                                      mPa.s at 100 s.sup.-1, 20° C.                                                             no thixotropy                                              ______________________________________                                    

All binders were water-miscible to an unlimited degree.

5. Comparison experiment

For the comparison experiment, a pigment paste resin whose synthesis isdescribed in EP Offenlegungsschrift 107,098 (Example II), wassynthesized.

235 parts (2.3 equivalents) of dimethylaminopropylamine were added inthe course of 1/2 hour to 420 parts (2 equivalents) of coconut fattyacid at room temperature. This caused the temperature to rise to about70° C. The reaction mixture was then refluxed at 135 to 140° C. forabout 2 hours.

The water of reaction was then distilled off using a water separator andexcess amine was finally removed in vacuo. The reaction product was thencooled to room temperature, diluted with 237 parts of butyl glycol,thoroughly homogenized and then treated with 218 parts of 90% lacticacid (2.18 equivalents). This caused the temperature to rise to about60° C. and the temperature was kept at this level for about 15 minutes.208 parts of demineralized water were then added, the reaction mixturewas thoroughly homogenized at 60° C. for 15 minutes and then 439 parts(2.34 equivalents) of Epikote 828 were rapidly added. The reactionmixture was then heated to 75 to 85° C. and kept at this temperature for2 hours. The product had an acid value of about 10 mg of KOH/g of solidresin and a solids content (1 h, 125° C.) of about 62%. The binder waswater-miscible to an unlimited degree.

6. Test of the binders prepared according to the invention as pigmentpaste resins:

a) Pigment pastes were prepared by standard test procedures from thebinders corresponding to the Examples 4.1., 4.2., 4.3., and thecomparison experiment 5 in accordance with the formulation below.

    ______________________________________                                        Pigment composition (including additives)                                     A                              B                                              ______________________________________                                         3.550  (a)      Surfynol ® 104(50%)                                                                          3.550                                                      in butyl glycol                                              10.542  (b)      basic lead silicate paste                                                                       10.542                                                      (75%) in demineralized                                                        water (EP 202)                                                1.692  (c)      Printex ® 25 (carbon black                                                                   1.480                                                      pigment)                                                      5.086           dibutyltin oxide  14.834                                     79.130  (d)      titanium oxide RSE 50                                                                           69.594                                     ______________________________________                                    

a) From Air Products and Chemicals Inc. (USA)

b) from Heubach

c) From Degussa AG

d) From Bayer AG

    ______________________________________                                        Pigment pastes:                                                                                                  Solids                                             Paste resin                                                                              Pigment         content                                    Example according to                                                                             composition                                                                              PBR  (1 h, 125° C.)                      ______________________________________                                        6.1.    4.1        A          12:1 70%                                        6.2.    4.2        A          12:1 70%                                        6.3.    4.3        A          12:1 68%                                        6.4.    5 (comp.)  A          12:1 80%                                        6.5.    5 (comp.)  B          35:1 70%                                        ______________________________________                                    

The paste resins were ground according to the above recipe in a ballmill by a method known to a person skilled in the art (see also DEpatent application P 3 726 497.4) and the solids content was thenadjusted using demineralized water in order to ensure appropriate easeof handling.

Virtually none of the pastes were thixotropic; their viscosities at D=50s⁻¹ were 300 to 450 mPa.s and at D=100 s.: 150 to 250 mPa.s. The pastesexhibited n significant viscosity changes or pigment drying even onstorage (4 weeks at room temperature).

b) The pastes were then added with stirring to a dilute clearcoat (20%aqueous solution) based on the EC binder dispersions described belowunder II and their solids content was adjusted to 18% (1 h, 125° C.)with demineralized water. The sieve residue was then determined atintervals of 24 hours, 14 days and 4 weeks (stirring at roomtemperature) and an L-shaped panel coating test was carried out.

The composition of the test paints and the subsequent results aresummarized in Table 4 further below.

II. Preparation of the binder dispersions (EC paints)

1. Synthesis of the curing agents (by analogy with DE patent applicationP 38 09 695.1)

102.3 parts (0.55 mole) of Beckopox®-080 (2-ethylhexyl glycidyl ether)were added to 129.3 parts (0.55 mole) of DETA(EO)₃ [DETA(EO)₃ =triplyethoxylated diethylenetriamine as described in the above patentapplication] in 116.80 parts of N-methylpyrrolidone in the course of 30minutes at 60° C. The temperature rose to 80° C. and the reactionmixture was kept at 100° C. (about 3 hours) until an epoxide value ofabout 0 was reached. The reaction mixture was then diluted with 449parts of toluene and cooled to 60° C. 819.5 parts (2.75 mole) of thepartly masked polyisocyanate according to I 1.) were added to thismixture in the course of 30 minutes and the reaction was then allowed toproceed for 4 hours at 70° C. until an NCO value of 0.15% was reached.

The amine value of the resultant curing agent was about 57.5 mg ofKOH/g.

Solids content (1 h, 125° C.) 65%

2. Preparation of the binder

2.1. By a method based on Example VIII/26 of DE Offenlegungsschrift3,624,454, a binder solution was prepared as follows:

832 parts of the monocarbonate of Epicote® 828 (diglycidyl ether) ofbisphenol A; 2 equivalents of epoxide), 830 parts of Capa® 205(=polycaprolactonediol with an average molecular mass of 830) and 712parts of toluene were mixed and caused to react at 70° to 140° C. in thepresence of about 0.3% of boron trifluorodietherate until an epoxidevalue of about 0 was reached. 1497 parts of the biscarbonate of Epicote®1001 (2 equivalents of carbonate, 70% suspension in toluene) were thenadded, the mixture was thoroughly homogenized and treated at 60 to 80°C. with 1192 parts of the compound according to Example I.1 in thecourse of 2 hours. The temperature was then kept at 80° C. until an NCOvalue of about 0% was reached.

The reaction mixture was then cooled to about 40° C., 645 parts ofbishexamethylenetriamine were added, followed by a further 596 parts ofthe compound I.1. added at 30 to 40° C. in the course of 2 to 3 hours;the reaction was then allowed to proceed at 40° C. until an NCO value of≦0.1% was reached.

The binder mixture obtained in this manner was adjusted to a 66% solidscontent using 1490 parts of methoxypropanol, heated to about 70° C. andkept at this temperature until an amine value of about 33 (based onsolid binder) was reached. The reaction mixture was subsequently partlyneutralized to an MEQ value of about 30 using 142 parts of 50% formicacid (solids content 65%, 1 hour, 125° C.).

2.2 By analogy with EP Offenlegungsschrift 12,463 and DEOffenlegungsschrift 3,615,810:

301 parts of diethanolamine, 189 parts of N,N-dimethylaminopropylamineand 1147 parts of an adduct obtained from 2 mole of2-methylpentamethylenediamine and 4 mole of glycidyl versatate (Cardura®E 10 from Shell) were added to 5273 parts of bisphenol-A epoxy resin(epoxide equivalent weight 475) in 3000 parts of ethoxypropanol. Thereaction mixture was kept at 60° to 90° C. with stirring for 4 hours andthen at 120° C. for 1 hour. It was then diluted (about 720 g) withethoxypropanol to a 65% solids content.

    ______________________________________                                        Hydroxyl value   276 mg of KOH/g of solid resin                               Hydroxyl value (primary OH)                                                                    55 mg of KOH/g of solid resin                                Hydrogenation iodine value                                                                     virtually zero                                               Amine value (tertiary amino                                                                    78 mg of KOH/g of solid resin                                groups)                                                                       ______________________________________                                    

3. Preparation of the paints:

The following dispersions (40%; 1 h, 125° C.) were prepared from thebinders described in II 2. by the recipe given below:

                  TABLE 3                                                         ______________________________________                                        Dispersion I       Dispersion II                                              ______________________________________                                        588 parts of binder 2.1.                                                                         1032 parts of binder 2.2.                                  (65% in toluene/methoxypropanol)                                                                 (65% in ethoxypropanol)                                    588 parts of binder 2.2.                                                      (65% in ethoxypropanol)                                                       363 parts of curing agent 1.                                                                     506 parts of curing agent 1.                               (65% in NMP/toluene)                                                                             (65% in NMP/toluene)                                       20 parts of butyl diglycol                                                                       20 parts of butyl diglycol                                 17.06 parts of 50% formic acid                                                                   32.2 parts of 50% formic acid                              1381 parts of demineralized water                                                                1389 parts of                                                                 demineralized water                                        ______________________________________                                         NMP = Nmethylpyrrolidone                                                 

The binder, the curing agent, the butyl diglycol and the formic acidwere taken, thoroughly homogenized and then 457 g (I) and 463 g (II)respectively of solvent were removed by vacuum distillation attemperatures of 40 to 80° C. (jacket temperature) and a minimum pressureof 0.02 bar in 50 minutes. To avoid foaming, the pressure was reducedappropriately slowly. At the end of the distillation atmosphericpressure was restored and the mixture was dispersed with warmdemineralized water at 60° C. with efficient stirring to a solidscontent of 40% by weight (determined at 125° C./1 h). The resultantlow-viscosity

dispersions were filtered at 40° C. through a 25 μm GAF filter. The MEQvalues were about 30 (I) and 35 (II) respectively.

The test combinations 1 to 10 were subjected to cataphoretic depositionin an open glass vessel. The indicated substrates were the cathode and ablank steel panel, at a distance of 5 to 10 cm from the cathode, was theanode. The temperature of the bath was about 28° C., deposition took 2minutes.

The assessment of the surfaces was carried out on cured films (bakingconditions: 20 minutes, object temperature

180° C.) with a theoretical film thickness of 2μm on B1. The results aresummarized in Table 4 below:

                                      TABLE 4                                     __________________________________________________________________________    Test   Clearcoat                                                                           Pigment                                                                            PBR of                                                                             Sieve residue after                                                                         L-shaped panel test                                                                         Coating on                 combination                                                                          dispersion                                                                          paste                                                                              the paint                                                                          24 hours                                                                           14 days                                                                           4 weeks                                                                            24 hours                                                                           14 days                                                                           4 weeks                                                                            A1 B1 B2 B3                __________________________________________________________________________    1        I   6.1. 0.4:1                                                                              10   30  80   pass pass                                                                              pass pass                                                                             pass                                                                             pass                                                                             pass              2        I   6.2. 0.4:1                                                                              10   25  60   pass pass                                                                              SM   pass                                                                             pass                                                                             pass                                                                             pass              3        I   6.3. 0.4:1                                                                              20   40  100  pass pass                                                                              M    M  pass                                                                             M  P                 4        I   6.4. 0.4:1                                                                               5   30  180  pass SM  M    M,P                                                                              pass                                                                             pass                                                                             D                              (comp.)                                                          5        I   6.5. 0.4:1                                                                              80   150 200  pass fail                                                                              fail B,O                                                                              P  pass                                                                             B,E               6      II    6.1. 0.4:1                                                                              20   20  50   pass pass                                                                              pass pass                                                                             pass                                                                             pass                                                                             pass              7      II    6.2. 0.4:1                                                                              30   30  40   pass pass                                                                              pass pass                                                                             pass                                                                             pass                                                                             pass              8      II    6.3. 0.4:1                                                                              30   50  50   pass SM  S    M  pass                                                                             pass                                                                             M                 9      II    6.4. 0.4:1                                                                              20   20  140  pass pass                                                                              SM   P,O                                                                              pass                                                                             P  P                              (comp.)                                                          10     II    6.5. 0.4:1                                                                              50   100 250  SM   S   fail B,P                                                                              pass                                                                             P  P,E               __________________________________________________________________________

The abbreviations in Table 4 have the following meaning:

    ______________________________________                                        pass    coating satisfactory, no sedimentation phenomena                      SM      slight matting                                                        M       matt film, still no process interference                              S       distinct sedimentation phenomena                                      fail    film unusable                                                         A1      aluminum                                                              B1      Bonder 132                                                            B2      Bonder 26                                                             B3      Bonder 26 - galvanized                                                PBR     pigment/binder ratio                                                  P       peaks                                                                 C       craters                                                               D       depressions                                                           O       overcoating                                                           B       coating break-up                                                      E       edge crawling                                                         ______________________________________                                    

The coating on the various substrates (A1 B1, B2, B3) was carried outunder identical deposition conditions and should not show anydifferences (Δ≧2 μm) in the film thickness (about 20 μm). Flow-out, edgecovering and matting of the fi1m must also be satisfactory.

It can seen from Table 4 that the pigment pastes according to theinvention satisfy the requirements regarding stability and coatingbehavior. The experiments carried out with the comparison pastesindicate (especially 6.5) that the pastes are less satisfactory inrespect of sieve residue and L-shaped panel test and that the highpigment-binder ratios tend to have an adverse effect (PRB about 35:1).

What is claimed is:
 1. Paste resins comprising (a) quaternary ammoniumgroups, (b) optionally hydroxyl groups, (c) optionally urethanes of theformula ##STR12## wherein R₅ is a hydrocarbon optionally interruptedwith --O--, and (d) groups of the formula (I) ##STR13## in which R¹ toR⁴ independently of one another represent hydrogen or a hydrocarbonradical of 1 to 10 carbon atoms, and X denotes hydroxyl or an urethaneof the formula ##STR14## the average molecular weight (Mn) of thesepaste resins (Mn) of these paste resins being 500 to 10,000.
 2. Thepaste resins as claimed in claim 1, wherein these paste resins containon average 1 to 4 of the groups (a) and 1 to 6 of the groups (d) permolecule.
 3. The paste resins as claimed in claim 1, wherein the numberof the groups (b) is on average 1 to 20 per molecule.
 4. The pasteresins as claimed in claim 1, wherein the number of the groups (c) inthe molecule is about 1 to 6 per molecule.
 5. The paste resins asclaimed in claim 1, wherein the urethane radicals (c) and X in theformula (I) are derived from monoisocyanates of 6 to 22 carbon atoms orfrom partly masked polyisocyanates of a total number of carbon atoms of10 to
 50. 6. The paste resins as claimed in claim 1, wherein the averagemolecular weight (Mn) is 1000 to
 5000. 7. The paste resins as claimed inclaim 1, which have hydroxyl values of 10 to 200 mg of KOH/g.
 8. Thepaste resins as claimed in claim 1, wherein the amount of quaternarynitrogen is 0.2 to 20 milliequivalents per gram.
 9. The paste resins asclaimed in claim 1, which are self-curing.
 10. A process for thepreparation of the paste resins as claimed in claim 1, whereinpolyamines (A) are first reacted with compounds (B) which contain atleast one cyclic carbonate group and, optionally, hydroxyl groups,1,2-epoxide groups and isocyanate groups, in such a manner that thisreaction product (C) still contains quaternizable amino groups, and thisreaction product (C) is then quaternized, optionally after a priorreaction with monoisocyanates of 6 to 22 carbon atoms or with partlymasked polyisocyanates still having one free NCO group.
 11. The processas claimed in claim 10, wherein at least one diamine from the group ofdiprimary diamines (A₂) and diamines (A₁) which contain a secondary ortertiary amino group in addition to a primary amino group, is used asthe polyamine (A).
 12. The process as claimed in claim 10, wherein asthe compounds (B) compounds of the formula (IV) ##STR15## are used, inwhich denotes a z-valent radical of a polyether, polyether polyol,polyester, polyester polyol, which can also optionally contain (NR¹³)groups, R¹⁵ representing hydrogen, alkyl of 1 to 14 carbon atoms orhydroxyalkyl of 1 to 14 carbon atoms, or denotes a z-valent hydrocarbonradical, preferably an alkylene radical of 2 to 18 carbon atoms whichcan optionally also carry inert or non-interfering groups, or denotes az-valent poly(sec.)amine radical or denotes the z-valent radical of areaction product of an epoxide-carbonate compound with polyamines,polyols, polycaprolactone polyols, hydroxyl group-containing polyesters,polyethers, polyglycols, hydroxyl function-containing, carboxylfunction-containing and amino function-containing polymeric oils havingaverage molecular weights of 800 to 10,000, polycarboxylic acids,hydroxyl function-containing or amino function-containingpolytetrahydrofurans and reaction products of polyamines with glycidylesters of α,α-dialkylalkanemonocarboxylic acids of the empirical formulaC₁₂₋₁₄ H₂₂₋₂₆ O₃ or with glycidyl versatate, denotes 1 to
 5. 13. Theprocess as claimed in claim 10, wherein (A₁), (A₂) and (B) are used inamounts of 28 to 80 mole %, 0 to 40 mole % and 20 to 60 mole %.
 14. Theprocess as claimed in claim 10, wherein the quaternization is carriedout by a reaction of (C) with a monoepoxide in an acid medium. 15.Pigment pastes comprising the paste resins according to at least claim 1and a pigment dispersed therein.